WASHINGTON -- With a two-sentence order, the Supreme Court provided a hint yesterday that graduating seniors at public schools may be able to say prayers at graduation ceremonies next year but can't count on doing so after that.

The order nullified a federal appeals court ruling that barred students from organizing religious devotions as part of graduation exercises. The Constitution forbids such prayers, whether organized by students or by school officials, the 9th U.S. Circuit Court of Appeals in San Francisco had ruled last fall.

The Supreme Court did not say that the ruling was wrong. But its brief order said the case on which the appeals court had acted is now legally dead, so the decision can no longer stand.

The issue, however, remains in dispute in lower courts and almost certainly will turn up before the justices again. Yesterday's order actually settled nothing.

Advocates of prayer in school were delighted. "The court's action," said Jay Alan Sekulow, chief counsel of the conservative advocacy group American Center for Law and Justice, "makes it clear that religious expression can occur in a school setting without creating a constitutional crisis." He said the decision reinforced his group's belief that when graduation prayer is student-initiated and student-led, it is free speech protected by the Constitution.

On the other side, opponents of school prayers argued that the court's action should not be misinterpreted. "All that means is that new challenges to graduation prayer will have to be filed," said Barry W. Lynn, executive director of Americans United for Separation of Church and State. "This is not an endorsement of student-led graduation prayers all over the nation."

While the controversy continues in the courts, Congress is considering a constitutional amendment to allow graduation prayers and other forms of religious expression in public schools.

After yesterday's order, there remains intact one federal appeals court ruling on the student-led prayer issue: a decision by the 5th U.S. Circuit Court of Appeals in New Orleans three years ago allowing such religious expression.

Because the appeals courts in New Orleans and San Francisco disagreed, the Supreme Court had been expected to step in to settle the matter. In January, the justices' first opportunity arose.

The San Francisco court's decision was challenged by a school district in the Idaho logging community of Grangeville. The Supreme Court examined that case twice in March, then put it aside for three months; that delay went unexplained.

The court left the case untouched until the only student still involved in the case as a challenger to prayers at Grangeville High -- Samuel Harris -- had graduated. He did so on June 2. Then, yesterday, the court acted swiftly, ordering the case dismissed as "moot." When a case becomes moot, courts no longer have authority to decide it.

Samuel's mother, Phyllis Wright Harris, a Forest Service worker in Grangeville, said in a telephone interview that "it's very frustrating: You work hard for what you believe in, and just because of a time limit it comes to no point."

Al Arnzen, the school superintendent for the district that includes Grangeville High, said of yesterday's order: "I don't think that solves the issue. We're right back to square one. I think it's a big issue; it is going to get dealt with sooner or later."

Gwendolyn H. Gregory, deputy general counsel of the National School Boards Association, said the court's action was "really a chicken move." She said that the court had ended the dispute between the lower appeals courts, and thus avoided the need to issue a ruling of its own. "I guess they just don't want to decide it; that's why I call it 'chicken.' "

The Supreme Court is expected to say something more later this week on its attitude about religion in public life.

Before recessing for the summer on Thursday, the court probably will decide cases that test when religious symbols may be placed in public squares, and when religious groups at state universities may share in student-activity fees.

Yesterday, the court acted on other cases, refusing to hear a constitutional challenge to a federal child pornography law requiring publishers of sexually explicit materials to disclose the ages of all their models, and turning aside a plea that the failed Bank of Credit and Commerce International's U.S. assets be returned to depositors instead of forfeited to the government.